Pressure-Retarded Osmosis Power Cell (2D)

This 2D cross-section simulator models a real pressure-retarded osmosis (PRO) membrane cell — the technology behind salinity-gradient "blue energy" power plants. A semipermeable membrane separates low-salinity river water from pressurized seawater; the osmotic pressure gradient between them pulls water molecules across the membrane while dissolved salt ions stay trapped on the seawater side. A live chart sweeps the applied back-pressure from 0 to the full osmotic pressure and plots the resulting power density, tracing the characteristic parabola that peaks exactly halfway. Adjust the salinity gradient, the membrane's permeability, and the applied pressure to find that power-density optimum — or push past it into the reverse-osmosis regime where the cell starts consuming energy instead of generating it.